Snap acting mechanism



June 18, 1963 J. P. WATSON 'SNAP' ACTING MECHANISM 7 Sheets-Sheet 1 Filed March 10, 1958 x wT E INVENTOR.

HERZ/c; a JESSUP,

A TTORNEKS.

June 1963 J. P. WATSON SNAP ACTING MECHANISM Filed March 10, 1958 7 Sheets-Sheet 2 JAMES R WATSON,

INVENTOR.

HERZIG d JESSUP,

ATTORNEYS.

7 Sheets-Sheet 3 J. P. WATSON SNAP ACTING MECHANISM June 18, 1963 Filed March 10, 1958 llllllll m JAMES P. WATSON;

INVENTOR.

HERZ/G a JESSUP, BY ATTORNEYS.

June 1953 J. P; WATSON sum ACTING macumxsm Fil ed March 10, 1958 Xi an! 7 Sheets-Sheet 4 m T E 0 SN AT W m J0 2W1 a n Y mm J H W W V SNAP ACTING MECHANISM 7 Sheets-Sheet 5 Filed March 10, 1958 INCRE ME N TS OF OPERA TING TRAVEL JAMES F! WATSON,

INVENTOR.

HERZ/G 8 JESSUP,

A TTORNEVS. BY

une 963 J. P. WATSON 9 SNAP ACTING MECHANISM Filed March 10, 1958 7 Sheets-Sheet 6 I I I: 15; f8

156 afl/UWUTW June 18, 1963 J. P. WATSON SNAP ACTING MECHANISM 7 Sheets-Sheet 7 Filed March 10, 1958 a w v v 1 1 \W \m 7/17 4 m I .l I u h .IIIL. 1-3m r I a m W H V 9 9 2 7 7 H U 1 -1 .l'lllv 4 W m m M Z a w z 4 MM United States Patent Office 3,094,594 Patented June 18, 1963 3,094,594 SNAP ACTING MECHANISM James P. Watson, Inglewood, Calif. (59 Waterway Road, Waterway Village, Jupiter, Fla.) Filed Mar. 10, 1958, Ser. No. 720,303 10 Claims. (Cl. ZOO-67) This invention relates to bi-stable mechanisms and particularly to a bi-stable electric switch.

It is an object of this invention to provide a bi-stable or snap acting mechanism employing fewer parts than heretofore required to achieve the same results.

It is another object of this invention to provide such a mechanism which is simple in design, not only in assembly but also in components, whereby punch-press manufacture of components may be effected.

It is a further object of this invention to provide a bistable mechanism and particularly a bi-stable switch wherein a given current capacity may be effected in a smaller size.

It is another object of this invention to provide a bistable mechanism wherein the operating travel and pressure are adjustable. This is particularly advantageous in that adjustment may be employed at the factory to compensate for manufacturing tolerances. The adjustments may he also used by the customer to adapt the switch to various actuating mechanisms or devices.

It is another object of this invention to provide a high current capacity in a 'bi-stable or snap acting switch having a very small body.

It is another object of this invention to provide a bistable mechanism having long life, minimum bounce or rebound, and high vibration resistance.

It is another object of this invention to provide a bistable or snap acting switch well adapted for plug-in use whereby it may be readily employed with printed circuits.

Yet another object of this invention is to provide new and improved mounting means for mounting a mechanism or a plurality of stacked mechanisms of the character described firmly and securely on a wall, panel or the like.

A further object of this invention is to provide new and improved mounting means for mounting such mechanisms which provides resilient pressure at advantageous points of the mechanism to afford greater stability in the mounting .and elimination of vibration or looseness therein without distortion of the housing or the mechanism.

In accordance with these and other objects which will become apparent hereinafter, preferred forms of the present invention will now he described with reference to the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view of one form of the present invention;

FIG. 2 is a longitudinal section taken at right angles to FIG. 1 .along the line 2-2 of FIG. 1;

FIG. 3 is an end view looking from the right in FIG. 2.

FIG. 4 is a view similar to FIG. 3, with the end cap removed;

FIG. 5 is a fragmentary perspective showing the resilient bi-stable leaf forming a component of the assembly shown in FIGS. 1 and 2;

FIG. 6 is a fragmentary longitudinal section of another form of the present invention, the remainder of the mechanism being substantially the same as in the first form except for the shape of the case;

FIG. 7 is a longitudinal section taken on line 7-7 in FIG. 6;

FIG. 8 is a cross-section taken on line 88 in FIG. 7;

'FIG. 9 is an exploded perspective view showing the resilient bi-stable leaf member and the cage or frame in which it is compressed and pivoted;

FIG. 10 is a fragmentary top view partially sectioned of still another rectangular form of the present invention, the remainder of the mechanism being substantially the same as the first form except for the shape of the case;

FIG. 11 is a longitudinal section taken at right angles to FIG. 10;

FIG. 12 is a fragmentary sectional view of still another form of the present invention;

FIG. 13 is a section taken on line 13-13 of FIG. 12;

FIG. 14 is a fragmentary section of still another form of the present invention;

FIG. 15 is an exploded perspective view of a portion of the resilient bi-stable leaf of FIG. 14;

FIG. 16 is a view of the leaf assembled and turned over from the position shown in FIG. 15;

FIG. 17 is an exploded partial view of another form of leaf member at the operating pivot point thereof;

FIG. 18 is a view similar to FIG. 17 showing the portions assembled together;

FIG. 19 is a fragmentary section showing the method of pivoting the leaf of FIG. 18;

FIG. 20 is an enlarged fragmentary view similar to FIG. 19;

FIG. 21 is a schematic diagram, in graph form, illustrating the relation of the length of the leaf to the contact pressure and operating travel;

FIG. 22 is a perspective view, in elevation, illustrating a further modified embodiment of this invention;

FIG. 23 is a perspective view, in elevation, illustrating a mounting clip adapted to mount the latter embodiment in a panel or the like;

FIG. 24 is an enlarged fragmentary side view thereof with parts broken away, illustrating the latter embodiment as installed in the panel;

FIG. 25 is a fragmentary horizontal cross-sectional view, with parts shown in elevation, as taken along line 25-25 of FIG. 24;

FIG. 26 is a view similar to FIG. 24, of a further embodiment of this invention;

FIG. 27 is an exploded view, in perspective, of a mounting means for mounting a switch of the type illustrated in FIGS. 6-8 to a panel or the like;

FIG. 28 is an end view, in elevation, illustrating the preliminary step in the installation thereof;

FIG. 29' is an end view similar to FIG. 28, illustrating the finished installation thereof; and

FIG. 30 is an end view similar to FIGS. 28 and 29, illustrating installation of a plurality of the latter switches.

Referring to the drawings, there is shown, in FIG. 1, a bi-stable mechanism housed in a cylindrical case or housing 21 preferably made of rigid insulating material. To the left end of the cylindrical casing 21 is shown formed as an integral wall 22 while the right end of the casing is closed by a cap 23 made of pliant resilient material. Mounted within the housing 21 is a rigid gen erally Ushaped frame or cage 24, having a pair of generally parallel arms 26 and 27. The bight portion of the U-shaped frame 24 is elongate and lies parallel with the case 21, while the arms 26 and 27 are disposed transversely thereof.

Spanning the arms 26 and 27 and generally paralleling the bight of the U-frame 24, is a bi-stable resilient leaf 28 made of springy metal, preferably having substantially the same coefficient of thermal expansion of frame 24. The arm 26 has a pivot means 29 for pivoting the left end of the spring 28 and the arm 27 has a pivot means 31 for pivoting the right end of the spring 28.

The pivot means 29 comprises a groove 32 formed in the inner face of the arm 26' in which ridesthe left end of the leaf =28 capped by a sheath 33 doubled over the left end of the spring 28 asshown in FIG. 5. The sheath 33' forms the actual bearing surface between the leaf 28' and the groove 32.

At its right end; the leaf- 28- is later-ally ensmalled, as shown in FIG. 5, to. form a pair of shoulders 34, one at each side of'the leaf- 28. Between the shoulders 34 the leaf 28 continues integrally to the right and is bent downward at right angles to form an arm 36, and thence is. bent back in serpentine fashion as shown at 37 and is anchored to a tab 38, extendingfrom theframe 24; being-bonded thereto at- 39: Thus a single integral structure extends from the sheath 3-3 around to the bond- 39.

That portion of theleafwhich is continued beyond and to the right of the pivot means 31- is-stilfened by an envelope 41 which has a pair of outwardly extending wings 42 sheathing theshoulders 34'- and forming a bearing surface with the bottom'of'a groove 43 formed on the inside face of the frame arm- 27. To accommodate the continued portion 36- of the leaf 28 a notch 45 is cut out ofthe arm 27. The transverse portion of the envelope 41 has a longitudinal ridge 44-to providean infinite number of pressure pointsfor. an operating boss to be described hereinafter.

The normal unstressed length of that portion of the leafspring 28' between the bearing or sheath members 33 and 4-2 is slightly greater than the distance between the grooves 32- and 43; so that the leaf 28-isforced to bow either upward or downward and is biased in bistable fashion either to itsupper. or lower attitude by the natural resiliency and stilfness of. the; leaf. Thestiffness of theserpentine-portion-37-biases-the'lower end'of the transverse portion 36' to theright (FIG. 2) thereby biasing the leaf 28 to the-lower of its two stablepositions, as shown in FIG. 2.

The radiused bearing surf-acesformedbythe sheaths at 33' and 42 serve to prevent undue abrasionand wear of their respective grooves.

The length-to-thiekness ratio of the leaf spring 28 is important to successful operation; If the leaf istoo rigid, separation of contact from t'erminal'may occur prior to snap-over-. Ifwthe'leaf is too flexible, the switch becomes more sensitive to vibration;

It has been found -that in using a alloy of'berryllium copper, infull hard condition and of .005 inch thickness, the most satisfactory range of lengths lies between .600and .800 inch.

As exemplified in the graph ofFIG. 21, in a leaf spring of such alloy and thickess, indicated by the line A, having a-lengthof. .625- inch, :an arch, .035 inch high and .l25-inch in diameter contacts centered .105 inch from theidling pivot, such as the end 33; in thegroove 32, the contact pressure is 7.2 oz., rising'to 11 oz., at-the moment; of snapover; indicated atA'. Line B represents a leaf identicalto spring. A.withthe exception that its length is .700' inch,.the contactpressure is 6.2 oz. rising to 12.8 oz., and subsequently decreasing to 1202. at the snapover moment B. A leaf denoted by C, having a length of .800 inch, has a contact pressure of 5.2. oz.,

4 rising to 12.2 oz., at which pressure the snapover, indicated at C, occurs.

A wave is advantageously formed in the spring during its flexing and prior to the snapover. The wave tends to increase pressure at the contact point until the snapover occurs, thus providing a firm electrical contact at the terminal until the snapover occurs.

The width of leaf will vary with the size of contact required. The contacts should be placed as near the idling pivot as contact gap requirements will allow. This places the contact mass nearer a point of support and allows more length of leaf from the operating pivot to the contact in-which to form the wave, which is so important to maintaining firm contact untilsnapover occurs.

Since the stiffness of a fiat leaf spring varies approximately as the cube of the thickness, and other factors such as hardness and type of. material. also affect this value, the length-to-thickness ratio will change for each type and thickness of material selected.

To actuate the mechanism an operating means or member is provided for engaging the stiffened portion-s 36-of the leaf 28 and pressing it against the bias of the spring 37 into its upper position-shown in phantom FIG. 2. In the forms shown in FIGS. 1-5 thisoperating. member consists of the cap 23-which isformedasa disc mounted for rotatable adjustmentover the open end of the house ing 21 by means of an inward bead 47 riding ina circumferential groove: 48 formed-in the housing 21. The cap 23 is mounted concentrically of the axis of the hous ing 21 Formed integralonthe-inner face of the cap 23 is a circular boss 49 disposed eccentricallyofthe axis of the: housing-21. The boss 49 engages the-ridge 44'. of armor. extendedgportion 36 toractuate the leaf 28. The cap- 23 isthickened in. the center. so as-to be sufficiently rigid-to transmitthe operating force from the exterior of the captothe. arm 36, while still pliant enough to-v allow the cap23 to be'pushedinwardly, thereby. operatingthe arm 36 through the intermediacy of the boss49; To-ene harrce the flexibility of the cap 23* for. operating. purposes, an annular corrugationi 51 isformed integrally. in the cap 23, thereby giving p'liancy. to the cap 23 for in and outmovement when the central button 52 is pressed inward;

The cap 23 may be rotated. in the groove-.48 andthe eccentric mounting of the boss 49 causes thebossr-to engage the armx36tat progressively. changing distances from the pivotpoint 31. inwthe leaf; 28. In' this way theeifective length of. the lever arm of theactuating member is changed" to adjust theoperatingtravel required of the operating member tosnap the leaf from one position to the: other; The operating. force required to: snap the switch will vary substantially inversely with the operating travel.

The cage or, frame 24. is held inpositionby. shoulders 53 extending from the inner. cylindrical walls of the easing 21', as bestseen in FIG. 4;and: also by a terminal 5.4,extending longitudinally fromthe frame. 24 through an opening 56 in the end wall 22.

In theforms shown in the .FIGS'. 1-.-5'-the;n1echanism is employedas a double throw switch and tothatend a pair of contacts57. and 58=are mountedrespectivelly on opposite sides of the leaf 28.-and .engagestati-onary contacts 5,9'and 61. respectively formed integral with terminals 62 and 63 respectively, which extend throughopem ings in theendwall 22., Theleaf- 28 thus constitutes a current-carrying arm of the switch but currentneed not be transmitted through either of the bearing surfaces at the end ofthe switch since the. serpentine portion 37 formed integral with the leaf 28 constitutes an integral circuit connection which is bondedv to the frame 24. at the point 39and:hence to the terminal 54.

In the operation of the switch,- inward pressure on the button-52 causes the boss 49 to be pressed inward by virtue ofth'e-pliancy of the cap 23; particularlyatthe corrugation 51. The boss 49 presses the arm 36 to the left, thereby pivoting the right-hand end of the leaf 28 clockwise in its pivotal mounting 43. This pivoting starts a wave or node traveling from right to left in the leaf. As this node reaches the contact 58 it measurably increases the contact pressure between 58 and 61. As the node passes the contact 58 the pressure becomes greatest and immediately thereafter a sufficient portion of the leaf 28 has been bowed upwardly to cause the leaf to snap to the upper of its bi-stable positions shown in phantom in FIG. 2. This breaks the contact between 58 and 61 with extreme rapidity and makes contact between the contacts 57 and 59. This wave action is similar to that which is more fully described in co-pending application Serial No. 575,467, filed April 2, 1956, now Patent No. 2,964,602 for Snap Acting Mechanism.

When pressure of the button 52 is relieved the bias from the serpentine pontion 37 causes the action to be reversed, this time with a rapid snapping away or separation of the contacts 57 and 59.

The cylindrical nature of the casing 21, coupled with the end placement of the terminals 54, 62 and 63, readily adapts the switch shown in FIGS. 1-5 to plug-in use.

'In FIGS. 6-9 a modified form of construction is shown wherein the right-hand pivotal mounting of the leaf 28a is effected in a somewhat diiferent manner.

In this form of the invention the frame 24a is continued longitudinally from the free end of the arm 27a with a portion 71 and then returns toward the center of the assembly with a transverse portion 72 finally terminating in a longitudinal section forming the terminal 54a, passing outwardly of the casing through a notch 73 formed in section 21a. Also in this form the case is made rectangular rather than circular and is formed of two longitudinally divided sections 21a and 211). A notch or slot 74 is formed in the portion 71 adjacent the arm 27a and a complementary slot 76 is formed in the upper surface of the arm 27a immediately adjacent the elongate or b ight portion. The two notches 74 and 76 permit the arm 27a to be bent back or forward slightly, thereby to adjust the spacing between the grooves 32a and 43a. This adjusts the compressing and arching of the leaf 28a with corresponding adjustment in the contact pressure and operating force required.

In this form a variation is also made in the leaf 28a in that the stiffening, instead of being effected by a separate piece 41, as in FIG. 5, is done by doubling the leaf itself back and forth upon itself, as shown at 36a. The leaf is then continued downwardly in a U-portion 37a, the end of which is bonded to the transverse portion 72 of the frame 24a.

The leaf 28a is snapped back and forth between its two stable positions by an actuating member 49a mounted for reciprocation transversely of the case by a pair of buttons 75 and 77 sliding in apertures 78 and 79 respectively. A slot or notch 81 is formed midway in the member 49a and brackets the stiffened operating portion 36a of the leaf 28a. Rounded operating bosses 82 and 83 are formed in member 49a on opposite sides of the stiffened portion 36a and engage it to press the leaf 28a back and forth and snap it between its two arched positions.

' To permit laterail stacking of switches the base is provided with complementary recess 86 and boss 87.

Where the leaf is ensmalled at the right-hand pivot the two shoulders are bent back as shown at 42a to provide radiused bearing surfaces riding in the grooves 43a. Where the leaf is folded back on itself at 36a the several layers are bonded together as by spot-welding shown at 80.

In the operation of the switch shown in FIGS. 69, downward pressing of the button 75 snaps the leaf 28a from its lower to its upper arched position, where it remains until the button 77 is pressed upward, whereupon it returns to its lower arched position.

In FIGS. and 11 there is shown a form of the present invention incorporating certain features of both the FIG. 1 and the FIG. 7 forms heretofore described. In these figures the leaf 2801 is continued past the pivot trunnion 31d and folded back and forth on itself to form a stiffened portion 36d. The leaf then continues in a downward serpentine portion 37d and is bonded to a base 121 formed integral with the frame 24d. Like the serpentine portion 37 shown in FIG. 2, the portion 37a? is springy or resilient like the major portion of the leaf 28d and there fore biases the stifiened end 36d upward.

The switch is actuated by a hexagonal button 122 reciprocally mounted in a grommet 123, which is in turn rotatably mounted in a bore 124 formed in the upper wall of the casing 21d. The grommet 123 is formed to provide frictional contact with the case 21d, while allowing free reciprocation of the plunger 122. The plunger 122 has adjacent its lower end an oblique flange 126, which in cooperation with a ledge 127 extending inwardly from the wall of the casing 21d, serves as an upper limit stop for the plunger 122. The opposite edge of flange 126 is stopped by frame arm 27d to limit downward movement of plunger 122. Beneath the flange 126 is a. downwardly projecting actuating button 128 which engages the stiffened portion 36d of the leaf 28d so that upon downward pressing of the plunger 122 the leaf is pivoted clockwise about the pivot means 31d and thereby snapped from its lower arched position to its upper arched position, as heretofore described in connection with FIG. 1. The leaf remains in its upper position as long as the plunger 122 is held down. Upon release of the plunger 122 the resiliency of the serpentine portion 37d biases the leaf counterclockwise and snaps it back to its lowermost arched position. The button 128 is disposed eccentrically with respect to the center line and axis 129 of the plunger 122. Thus, rotatable adjustment of the plunger 122 serves to move thebutton 128 toward or away from the pivot point 31d; thereby altering the effective lever arm between the contact point of the button 128 and the pivot point 31d. This effects adjustment of the travel stroke required of the plunger 122 with corresponding inverse adjustment of the operating force required.

The bore or passage in the grommet 123 through which the hexagonal button plunger 122 extends is of mating hexagonal configuration, so that rotation of the plunger 122 as by a small wrench, also rotates the grommet 123. The upper flange 131 of the grommet 123 is provided with an index mark 132 which cooperates with a series of numbers 133 marked on the case 21d and indicating the button travel required to actuate the switch at that particular angular setting of the plunger 122. The flange 131 is circumferentially ensmalled at 134 to cooperate with a stop 136 on the case 21d to limit angular adjustment of the plunger 122.

The angle of the oblique flange or shoulder 126 automatically adjusts the upper and lower stops to suit the length of operating travel selected.

In FIGS. 12 and 13 another form of the present invention is shown, this being a variant of the form shown in FIG. 7 wherein upward arching or bowing of the leaf 282 is effected by the right hand button 76e and return of the arch to its lower position is effected by the left hand button 77c. As noted, the two buttons operate on opposite sides of the pivot point 31a and to that end the stiffened portion 362 of the leaf 28e is extended so as to be substantially symmetrical about the pivot 31e and thereby give a stiffened operating surface for each of the buttons 76e and 77s.

The form of the invention shown in FIGS. 12 and 13 permits switch operation, both forward and backward from one side of the casing 21e rather than requiring actuation from both sides, as in the case of FIG. 7.

In the form of the invention shown in FIGS. 14-16 the leaf 28b is not ensmalled laterally to form shoulders constituting the right hand pivot, but instead the leaf continues straight through past the pivot with a uniform unbroken width, as best seen in FIG. 15. The pivot is formed by a two-part stiffener consisting of an upper plate 91 having a pair of wrap-around wings 29- and lower plate 93 having lateral tabs 94 folded double for added strength and to provide a radiused bearing surface 96. The wings 92 encircle both the leaf 28b and the sheet 93 as shown in The resulting assembly not only strengthens the leaf 2812 at. the point where it will be operated by the operating member 495, but also clamps in place the tabs or wings; 9'4; constituting the pivot trunnions.

To-secure-the assembly against longitudinal slipping on the leaf. or spring 28ba transverse indentation 97 is formed across the entire assembly.

'Iihis'form: of the invention has an advantage over the previous forms in. that there is no inside corner formed in the leaf proper which might form a point of maximum stress and a possible start for fracture.

The actuating member 49b constitutes a'button operatingthrough a somewhat springy loop 98, and onto an operating finger 99 bearing against the overlay 91 and sliding in a groove or slot in a ledge 101 formed in the frame 24b. 7

It will benoted in the form of the invention shown in FIG; 14 thatthe U-shaped frame 24b is turned at right angleswith respect to the leaf 28b from the position of the frames 24 and'24a-in-the forms previously described; that is' to say, in-the earlier forms the frame occupied generally thesarnepl-ane asthe'leaf 28,.whereas'in the form shown in FIG. 14 the'frame or more specially the bight portion of the frame is spaced from the plane of the leaf 28b; This structure has theadvantage that either arm,- as for exampleth e arm.27b,- may be readily adjusted by being bent-atitsjuncturewith the bight portion 24b without the special provision of notches, as described hereinbefore.

Asrin the formshown in FIG. 1, the return or shunt portion-isof the same springy; constituency; as the leaf 28b with: which it is integrally formed, so that it constitutes areturn -biasurging the spanning portion of the leaf 28b to its downwardly bowed position (FIG. 14).

V In-FIGS, l7-20 afurther form" of pivotal mounting is illustrated wherein the trunnions are eliminated entirely and-instead, a slotor rectangular opening 106 is formed in thestraighhthrough-leaf 28c and strengthened by a plate 107, the Wings 108 of. whichare bent around the leaf 28c asshownin FIG. 18; A tab 109 is lanced downwardly of plate10'7 leaving an opening 111 registering with the opening106. The tab 109-is bent around the edge of the'opening'106 thereby forming a radiused bearing surface 112-.which bears against a curved groove 113 formed-in a post 270 that extends upwardly from the frame 24c and passes through the opening 106; As in the other embodiments, the leaf 280 is continued integrally iii-serpentine fashion as shown at: 37's to form a return spring and electrical shunt which'is riveted to the frame 24a at 114;

Asseen in FIG. 20 the-openings 106 and 111 are made suflicientlylarge-to pass the post 270 taking into account the bent-baek tab 109; Notches 116 formed in opposite sides of the wings108, form a registering opening with the. openings-106 and 111 (FIG. 20).

Referring to FIGS. 22-25, another embodiment of this invention is illustrated, wherein a cylindrical case or husing 0.1 is substantially similar to the housing 21, of the first describedembodiment (FIGS.- 1-5),,with the exception of a pair of oppositely disposed longitudinal grooves lkprovidedon the externalsurface of the housing. A mounting clip 151, having a-cylirndrical portion 152 and atpair of elongated, rearwardly extending arms 153, may be advantageouslyused to secure the housing within an aperture 154 ofa panel 156 or the like. The aperture 1'54=is-preferably; reamed or otherwise drilled to receive the cylinder 21 in=a very close fit to reduce vibration.

In order to secure the cylinder 21 within the panel 156,

the cylindrical portion 152 of the clip 151 is slipped over the cap 23 to abut shoulders 157 of the housing 21', with the arms 153 extending rearwardly and residing one within each groove 150. The housing 21 is then inserted into the'panel 156 and the arms are bent back as indicated at 158' to abut the rear surface 161' of the panel 156 to retain the housing within the aperture v154, and prevent longitudinal movement therein.

The arms are preferably provided with a plurality of oppositely facing notches 159 which provides bevelled edges at the ends=of the arms if clipped or cut transversely thereat.

Refenring to FIG. 26, 1a modified embodiment is disclosed wherein a cylindrical band 160 is telescopingly dispo'sed over the" housing 21 to abut the rear surface 161 of the panel, and'overlie the arms 153 of the clip 151. In instant embodiment, to secure the housing 21 from longitudinal movement, the arms 153 are bent back over the band 160 as indicated at 162, whereby the flanges "157 are clampged to the panel I156 between the bands 152 and 160. The portions .162 are preferably bent to a position substantially parallel to the arm portions within the grooves 150 and may be trimmed or clipped transversely, as previously described, at a convenient set of notches 1159.

Referring to FIGS. 27-30 inclusive, another form of mounting clip is illustrated which is more specifically adapted for mounting the rectangular form of switch, shown in FIGS. 6-8 inclusive, to a-panel, or the like, indicated at 170.

The mounting 'clip, generally indicated by the numeral 171, comprises a unitary length of substantially resilient wire, preferably of stainless steel or the like, which is bent as illustrated toform a pair of spaced, substantial-1y paralleltends or dowels 172 and a pair of oppositely-extending bight portions 173 angular-1y disposed relative to the dowels 172..v The bight portions, together with an interconnecting portion form a generally Z-shaped configuration' or, more specifically, interconnected oppositely extending bent portions whose apices or bights extend to opposite edges of the housing.

Each ofth'e-bight portion 173 is transversely bent in a plane substantially less than 90 relative to an adjacent end or dowel 1 72 to form resilient presurepoints against the housing 174 when installed, and is preferably of a'length suitable for reaching an opposite edge region of the switch housing 174. Pressure is thereby applied at the edges reinforced by the sidewalls 175 of the housing rather than in a central. unsupported varea thereof, 4 as will hereinafter be described, thus preventing inward distortion of the housing which rn'ight'otherwise result.

The mounting clip 171 is adapted to secure 'thehousing 174 to the panel by installing the clip in such manner that the ends or; dowels v172 extend through apertures 176 provided adjacent diagonally opposed corners of .the housing 174 and aligned apertures *177 of the panel, with the bight portions .173 overlying the outer sidewall :178 of the housing. The dowels .172 are. preferably of sufiicient length to extend substantial-1y outwardly of the face of the panel 170 opposite the switch (as seen in FIG. 28) whereby the ends of the dowels may be grasped as by long-nosed pliers, or the like,-to pull the dowels outwardly of the panel'withsufficient force to create a pressure of the bight portions 173 on the housing 174. The ends of the dowels 172 are subsequently, bent back on themselves to form inwardly-extendingt-abs 179 (FIG. 29 for securing the housing 174 to the panel 17 0 while retaining the resilientpresure of the bight portions .173 against the side Wall 178 of the housing.

The apertures .176 are preferably located adjacent 0pposite corners of the housingwhich are supoprted by the side walls of the housing 174.

In order to facilitate stacking of a plurality of housings 174 during the instalaltion, the dowel portions 172 are preferably of sufiioient length to extend through more than one housing, as illustrated in FIG. 30. Such additional length of dowel may be cut off to appropriate length if it is desired to mount only one such housing. A unitary mounting clip 171, as described above, advantageously eliminates necessity for screws which require specific lengths for secure installation, and, being unitary, there is nothing to come loose. Futrhermore, the Z-shaped configuration provides continual spring tension which compensates for any differential in expansion and contraction and provides added length for greater resiliency which is aplicable to portions of the housing which are supported and reinforced by side walls. This instant form of mounting clip also provides a dowel type securement by extending through instead of around the housing.

The recess 86 and boss 87 (FIG. 8) may be eliminated, if desired, when the instant clip 171 is used, since accurate alignment for stacking may be achieved through alignment of apertures 176.

While the instant invention has been shown and de scribed herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departure may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent methods and apparatus.

What is claimed is:

l. Snap-acting switching mechanism comprising: frame means having opposed Spaced pivot means, a leaf spring compressed and bowed by the said pivot means thereby to arch said leaf spring into one or the other of two positions, said leaf spring continuing integrally past one of said pivot means, the continued portion of said leaf spring being stiffened by over-lying said continued portion with a sheet of material folded through substantially 180 degrees into position against the continued portion, so that the continued portion is appreciably more rigid than the major portion of the part of said leaf spring spanning said pivot means, said folded sheet of material forming radiused bearing surfaces engaging said one pivot means, and movable operating means for engaging the stiffened portion of said leaf spring and for pivoting the same about said last mentioned pivot means, thereby to effect snapping of the leaf spring from one arched position to the other.

2. Bi-stable electric switch comprising frame means having spaced opposed pivot means, conducting leaf means adapted to carry current spanning said pivot means and being pivoted thereby, said leaf means being compressed between said pivot means to form an arch and being capable of snapping from one position to another, said leaf means extending beyond "one of said pivot means, the extending portion of said leaf means being relatively stiifer than the major portion of said leaf means which spans said pivot means, and constituting at least a portion of a circuit connection to a terminal of the switch and integral with said leaf means, and operating means for engaging the extending portion of said leaf means and for flexing said leaf means from one arched position to the other.

3. Bi-stable electric switch comprising frame means having spaced opposed pivot means, conducting leaf means adapted to carry current spanning said pivot means and being pivoted thereby, said leaf means being compressed between said pivot means to form an arch and being capable of snapping from one position to another, said leaf means extending beyond one of said pivot means, the extending portion of said leaf means being relatively stiffer than the major portion of said leaf means which spans said pivot means, and constituting at least a portion of a circuit connection to a terminal of the switch and integral with said leaf means, at least a portion of said circuit connection being resilient and biasing said leaf means toward one of its arched positions, and operat ing means for engaging the extending portion of said leaf 10. means and for flexing said leaf means from one arched position to the other.

4. Bi-stable mechanism comprising frame means having opposed pivot means, leaf means bowed and compressed between said pivot means into one or the other of its two arched positions, a portion of said leaf means extending beyond one of said pivot means and being stiffened to form an operating means for the mechanism, an operating member reciprocable substantially normal to the extending portion of said leaf means, means for mounting said operating member for rotation about its axis of reciprocation, said operating member engaging said extending portion at a point spaced radially from said axis, whereby rotatable adjustment of said operating member effects movement of said engaging point toward and away from said one pivot means, thereby to adjust the effective operating lever arm of the mechanism.

5. Mechanism in accordance with claim 4 wherein said operating member comprises a disc-like member disposed concentrically of said axis of reciprocation, an annular portion of said disc-like member being sufiiciently flexible to allow the center portion of said member to be flexed inwardly toward said continued portion of said leaf member, said disc-like member having a curved boss spaced eccentrically of said axis of reciprocation and engaging said continuing portion of said leaf member, whereby rotatable adjustment of said disc-like member continuously adjusts the engagement point between said boss and said continued portion, with the point of engagement continuously shifting with respect to said one pivot means, thereby to adjust the effective operating lever arm of the mechanism.

6. Bi-stable mechanism comprising a generally cylindrical housing, pivot means spaced longitudinally within said housing, resilient leaf means spanning and compressed between said pivot means into one or the other of two arched positions, a portion of said leaf means continuing beyond one of said pivot means and being turned at substantially a right angle to said leaf means, an operating member disposed in the end wall of said housing and being mounted for reciprocation along the axis of said housing, said operating member having :an operating boss on the inner face thereof engaging said extended portion of said leaf member, said operating member being rotatably adjustable about said axis and said operating boss being disposed eccentric to said axis, whereby rotatable adjustment of said operating member effects adjustment of the operating lever arm of said mechanism.

7. Bi-stable electric switch comprising: frame means having spaced opposed pivot means, first conducting leaf means spanning said pivot means and being pivoted thereby, said leaf means being compressed between said pivot means to form an arch and being capable of snapping from one position to another, and second conducting leaf means in electrical connection with said first leaf means and extending away from one of said pivot means, the extended end of said second leaf means being fixed with respect to said frame means and constituting a terminal of the switch.

8. Bi-stable electric switch in accordance with claim 7 wherein said second leaf means is resilient and biases said first leaf means toward one of its arched positions.

9. Switch in accordance with claim 7 wherein said second leaf means is serpentine in configuration.

10. Switch in accordance with claim 7 having a stationary contact engaged under pressure by a moving contact carried on said first conducting leaf means, said first conducting leaf means having a lengthto-thickness ratio such as to cause, during operation of said switch, a continuous increase in said pressure until said snapping occurs.

(References on following page) 1 1 References Cited in the file of this patent UNITED STATES PATENTS I Hollis Sept. 25, 1951 Pck'e't all Ndv. 21 I882 M'o'ttl'a'u -5 May" 8, 1928 Thomas" Mar. 10', 1931 Taylor Aug. 13, 1940' Mape's Mar. 21, 1944 Kronrniller Jan. 3, 1950 10 Martin Mar. 12, 1957 FOREIGN PATENTS Switzerland Aug. 15-, 1935 France July 18, 1949 France Sept. 2, 1957 Great Britain Oct'.-2, 1957 GreatBIitain Mar. 23, 1953 

1. SNAP-ACTING SWITCHING MECHANISM COMPRISING: FRAME MEANS HAVING OPPOSED SPACED PIVOT MEANS, A LEAF SPRING COMPRESSED AND BOWED BY THE SAID PIVOT MEANS THEREBY TO ARCH SAID LEAF SPRING INTO ONE OR THE OTHER OF TWO POSITIONS, SAID LEAF SPRING CONTINUING INTERGRALLY PAST ONE OF SAID PIVOT MEANS, THE CONTINUED PORTION OF SAID LEAF SPRING BEING STIFFENED BY OVER-LYING SAID CONTINUED PORTION WITH A SHEET OF MATERIAL FOLDED THROUGH SUBSTANTIALLY 180* INTO POSITION AGAINST THE CONTINUED PORTION, SO THAT THE CONTINUED PORTION IS APPRECIABLY MORE RIGID THAN THE MAJOR PORTION OF THE PART OF SAID LEAF SPRING SPANNING SAID PIVOT MEANS, SAID FOLDED SHEET OF MATERIAL FORMING RADIUSED BEARING SURFACES ENGAGING SAID ONE PIVOT MEANS, AND MOVABLE OPERATING MEANS FOR ENGAGING THE STIFFENED PORTION OF SAID LEAF SPRING AND FOR PIVOTING THE SAME ABOUT SAID LAST MENTIONED PIVOT MEANS, THEREBY TO EFFECT SNAPPING OF THE LEAF SPRING FROM ONE ARCHED POSITION TO THE OTHER. 